Animal liberationists have chained themselves to the cages at a chicken farm in New South Wales' Lower Hunter Valley, protesting against what they say is the poor treatment of the animals.

The protesters, from Animal Liberation New South Wales, earlier this morning freed 30 of the egg-producing chickens which they say are now being attended to by a vet.

The group's executive director, Mark Pearson, has called on the Government to legislate a requirement that stock animals such as chickens must be able to exercise.

He says the group is negotiating with police and is trying to arrange a formal inspection of the farm.

"I contacted the police myself because they have powers under the Prevention of Cruelty to Animals Act and also they have the power to be able to bring about some sort of intervention and mediation between ourselves and Pace management," he said.